This article describes a problem in which you receive an "invalid product key" error message when you try to start one of the following:

• A Microsoft Office 2003 program after you install a Microsoft Office 2003 suite
• A Microsoft 2007 Office program after you install a 2007 Microsoft Office suite

To work around this problem, remove the previously installed Office suite or individual programs. Then, do one of the following:

• Install the version of Microsoft Office that you want.
• Start an Office program if the version of Office that you want is already installed.

This article is intended for a beginning to intermediate computer user.
You may find it easier to follow the steps if you print this article first.

When you try to start an Office 2003 program after you install an Office 2003 suite, or you try to start a 2007 Office program after you install a 2007 Office suite, you are prompted to provide a product key. After providing the product key, you may receive the following error message: Or, you may experience the following symptom. Office 2003 or a 2007 Office suite seem to have installed correctly. When you try to activate Office over the Internet, the activation process stops responding (hangs). In this case, you receive the following error message:

This problem may occur if the following conditions are true:

• You have another Office 2003 suite or 2007 Office suite or individual Office program preinstalled on the computer.
• A trial version of an Office 2007 suite is installed on the computer. The computer manufacturer may have preinstalled a trial version of an Office 2007 suite. For example, Microsoft Office 2007 Home & Student Trail or the 2007 Microsoft Office system may have been preinstalled. You may receive the error message in the "Symptoms of the problem" section if you did not uninstall a trial version of Office 2007 before you installed a retail version of Office 2007.
• You have not started any one of these Office 2003 programs or 2007 Office programs before.

To work around this problem, uninstall any unnecessary Office suites. This includes trial versions and individual programs.

Step 1: Start Add or Remove Programs

1. Click Start, and then click Run.
2. In the Open box, type appwiz.cpl.
3. Click OK.

Step 2: Remove Office suites or individual programs

1. In the Currently installed programs list, locate and then click either the previously installed Office suite or the individual Office program.
   
   Note This includes any trial versions of Office 2007 that were preinstalled by the computer manufacturer. For example, the computer manufacturer may have preinstalled 2007 Microsoft Office system or Office 2007 Home & Student Trial.
2. Click Remove.
3. Click Yes when you are prompted to confirm that you want to remove the Office suite or individual program.

Step 3: Start any Office program and re-enter the product key

Retail versions of Office are self-repairing. To repair the version of Office that is installed, start any Office program and follow the instructions to enter the product key. To do this, follow these steps:

Note If a retail version of Office is not installed, go to step 4.

1. Exit any programs that are running and close all open windows.
2. Start an Office program. For example, start Microsoft Office Word or Microsoft Office Excel.
3. Type the product key for the retail version of Office when you are prompted.

Step 4: Reinstall Office

In some cases, you may have to reinstall Office.

1. Click Start, and then click Run.
2. In the Open box, type Appwiz.cpl, and then click OK.
3. In the Add or Remove Programs dialog box, click Add New Programs.
4. Click CD or Floppy.
5. In the Install Program From Floppy Disk or CD-ROM dialog box, make sure that the Office CD is in the CD drive or DVD drive, and then click Next.
6. Click Finish, and then follow the instructions to complete the installation of Office.
7. Click OK when the Office Setup has finished.
8. Remove your Office CD from the CD drive or DVD drive.
9. Start an Office program, and then type the Office product key when you are prompted.